Automatic telephone system.



C. L. GOODRUM.

AUTOMATIC TELEPHONE SYSTEM. APPLICATION FILED JAN-3.1916.

Patented Jan. 29, 1918.

2 SHEET$SHEET I.

SQ/QCTOP Line Finder I C. L. GOODRUIVI. AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED JAN-3.1915- Lfi5%fi@@ Patented Jan. 29, 191&

2 SHEETS-SHEET 2.

Je/eafor cHm-tns I... aoonnura,

or atnwrona, at. r, ass'ren'on 'ro wnsrnnu gnrncrnre coatraam, INCORPORATED, O1! NEW YORK, W: Y., A CORPORATION O15 NEW YORK.

aurona'rrc anthracite srs'rnat.

fipeclfleation of Letters IlPatent.

Patented at. aa, rare.

application med tanuary a, 1916. Serial No. 69,920.

To all whom it may concern:

Be it known that. l, Cnannns L. Gooomum, a citizen of the United States, residing at New York in the county of New York and State of hlew. York, have invented certain new and useful Improvements in Automatic Telephone Systems, of which the following is a full, clear, concise, and exact descriptlon.

This invention relates to automatic telephone systems of the two-wire multiple type-that is, automatic systems inwhich but two wires (the talking conductors) are multipled through the various switches used in establishing a talking connection. A system of this general character is disclosed in an application of Charles L. Goodrum, Serial No. 35,326, filed June 21, 1915. One Of the features of this invention resides in the provision, in a system of the above character, of means for repeating impulses calling subscribers sending device over a portion of the talking trunk physically disconnected from the calling subscribers line. A-further feature of the invention resides in the means for eliminating, as far as possible,

the impulse or stepping relays. The invention also comprises other features which result from or are incident to the features above noted. Figures 1 and 2 of the drawings, with Fig. 1 at the left, show the circuits of the invention and diagrammatically indicate the apparatus employed therewith.

Any step by step, two-movement switch may be employed with the circuits shown. A switch of this general character is shown in the patent to Keith and Erickson, No. 815,175, although a switch such as disclosed in an application of Henry F. Dobbin, Serial N 0. 46,855 filed Aug. 23, 1915 will preferably be employed. With each switch a circuit changing device for controlling certain operatlng circuits at its respective switch is employed. These devices may be of the general character of the switch shown in the above mentioned patent and referred to therein as a side switch, but a circuit controlling device such as shown in an application of Oscar F. Forsberg, Serial No. 6302, filed February 5, 1915, will preferably be employed. Such a circuit changing device may be caused to effect circuit changes, either upon the energization or upon the deenergization of its controlling or escape magnet, as described in said Forsberg application.

from the Each line is provided with a line relay 1 and a cut-off relay 2, and, when desired, with a register magnet 3. The lines of the exchange are arranged in groups of ten each, and for each group of ten lines the .controlling devices shown in the dotted rectangle at the lower left corner of Fig. 1 are vided. The apparatus within this dotted rectangle is common to all the ten lines of the group. The test relay 4 is not only com-. mon to the lines in the group but may be used to control any of the group of linefinder switches which have access to the lines of the group. The switches employed in the present embodiment of the invention are one hundred line switches, ranged in ten groups group.

of ten contacts In a prothe contacts bein ar 7a As the circuits employed in this system are from the following description in which the establishment of a successful and an unsuccessful connection is described, and also the manner of release in both instances.

We will assume that the subscriber at the station shown at the left in Fig. 1 desires to establish a talking connection to the subscribers line shown at the right in Fig. 2. Upon the calling subscriber removin' his receiver from the-hook a circuit is comp eted from battery through the left winding of relay 1, back contact and left armature of relay 2, over the subscribers line through the substation thereof, back over the right side of the line, through the right armature and back contact of relay 2 and back to battery, through the right winding of relay 1. Relay 1 attracts its armatures and completes a circuit from battery, over relay 5, contact and left armature of relay 6, left armature and contact of relay 4, contact and right armature of relay right winding of relay 1. Relay 5 attracts its armature and locks up through its left armature and contact. Relay 5 at its outermost right armature places round potential upon the test contact of tlie group of the calling line. It also completes a circuit from battery through rotary stepping magnet 7, its individual interrupter 8, side switch wiper 9, relay 6, innermost right armature and front contact of relay 5 to ground, through the armature and contact of relay 1 to ground through the TOO ing line a circuit is completed from battery through escape magnet 13, side switch wiper I4, brush 12, the group contact 15, outermost right armature and contact of relay 5 to ground through the right armature of relay 4. The escape magnet is energized and moves the side switch to position 2, thus interrupting the circuit for the rotary ma net 7 and completing a circuit for the vertical stepping magnet 16 from battery through said magnet, its individual interrupter 17, side switch wiper 9, relay 6, innermost right armature and front contact of relay 5 to gyround through the armature of relay 4.

nder the control of magnet 16 the brushes 10 and. 11 are stepped from line to line in the group of the calling line. In position 2 of the side switch an energizing circuit is provided for the escape magnet 13 throu h side switch wiper 14 in parallel with the vertical magnet 16. The energization of the escape magnet throu h this circuit, however, does not move the s1de switch out of position 2. When the finder switch brushes 10 and 11 engage the contacts of the calling line, acircuit is completed from the source of current 18, through the test relay 4, left contact and armature of line relay 1, the lower winding of the register magnet 3 to the test contact .of the calling line, and thence through brush 11, -wiper 26, condenser 19, and winding 20 of the repeating coil to ground. The relay 4 will be energized by the impulse of current in this circuit, but the magnet 3 will not attract its armature. The attraction of the right armature of relay 4 interrupts the stepping circuit for the vertical magnet 16 and also for the escape magnet 13, which, in becoming deenergized, moves the side switch to position 3. Relay 4 at its right armature interrupts the holding circuit for relay 5. In position 3 of the s1de switch a circuit is completed from battery through the upper winding of register magnet 3, cut-off relay 2, brush 10, side switch wiper 21 and winding 20 of the repeating coil to ground. The cut-off rela 2 will be energized over this circuit and wi l interrupt the circuit for the line relay 1. The line relay will retract its armatures and the common control apparatus within the dotted rectangle will all return to its normal contact and thus be free for use in controlling the connection of another finder switch to a second callin line in the same group as the subscriber w 0 has just called.

It may be here noted, in regard to the register magnet 3, that the windings are so a justed that current through eit er winding alone will not serve to attract its armature, but it will only operate when the effect of current through both windings is accumulative.

When the finder side switch moved to position 3, a circuit was completed from battery through resistance 22, side switch wiper 23, relay 24, through winding 25 of the repeating coil, side switch wiper 26, brush 11, the lower winding of register magnet 3, the front contact and left armature of relay 2, over the left side of. the subscribers line, through the substation apparatus thereat, back over the right side of the subscribers line, through the right armature and front contact of cut-off relay 2, brush 10, wiper 21 and winding 20 to ground. Relay 24 will be ener ized over this circuit but as the attractive orce produced by the current through the lower winding of magnet 3 opposes that produced by the current through its upper winding magnet 3 is not efl'ected. The attraction of the ri ht armature of relay 24 completes a circuit for relay 27. The calling subscriber now operates his dial to produce a series of interruptions in the line circuit each of which causes the momentary deenergization of relay 24. With each denergization of relay 24 a circuit is completed from battery through the rotary magnet 28 and from battery through the escape magnet 29 and wiper 30 in parallel and thence through wiper 31, innermost armature and back contact of relay 24 to ground through the front contact and left armature of relay 27. Relay 27 and magnet 29 both being slow, remain energized during the series of impulses. The rotary magnet 28, however, is repeatedly energized and-deenergized stepping the brushes 32 and 33 of the first selector switch from group to group of trunk terminals.

Upon the termination of the series of impulses, the relay 24 remains energized, thus holding open the circuit for the escape magnet 29 which become deenergized and moves the side switch to position 2. As the relay 24 is only momentarily de'e'nergized in the normal operation of the system, the relay 27 will remain up until the calling subscriber replaces his receiver on the hook.

In position 2 of the first selector side switch a circuit is completed from battery through vertical magnet 35, its individual interrupter 36, contact and armature of magnet 29, side switch wiper 37 and front contact and left armature of relay 27 to ground. Magnet 35 is repeatedly energized and deenergized thus steppin the brushes 32 and 33 from trunk to trun When the terminal of an idle trunk is engaged by brush 32 a circuit is completed from battery through escape magnet 29, wiper 30, wiper naaaaeo 38, brush 32, resistance 39 and relay 40 in parallel to ground through side switch wiper 41, and the side switch is thus moved to position 3. Relay 40 is energized and completes a circuit from battery through escape magnet 42 and side switch wiper 43 thus moving the side switch of the second selector to second osition. In position 2, high resistance 81 is included in the circuit of relay 40 by tracts its armature. The calling subscriber now operates the dial to send the next or hundreds series of impulses. With each deenergization of relay 24 a, circuit is completed from battery through the rotary magnet 44 and from battery through escape magnet 42 and wiper 43 in parallel therewith and thence through Wiper 45, brush 33, wiper 31, armature and back contact of relay 24 to ground through the front contact and armature of relay 27. The brushes 46 and 47 are stepped from group to group of trunks terminating in the final selectors. Upon .the termination of the series of impulses relay 24 remains energized thus holding open the circuit for the slow release escape magnet 42, which falls off moving the side switch to position 3.

A circuit is now completed from battery through the vertical stepping magnet 48, its interrupter 49, side switch wiper 50 and contact and armature of magnet 42 to ground. The switch brushes are thereupon ste p'ed from trunk .to trunk until the brush 4% engages the terminal of a trunk leading to an idle connector switch, when a circuit will he completed from battery through escape magma; 42, wiper 43, (position 3), resistance 51 and relay 52 in parallel to ground through side switch wiper 53. Magnet 42 and relay 52 are both energized. Magnet 42 moves the second selector side switch to position 4. Relay 52 closes a circuit from battery through relay 54 and side switch wiper 55; relay 54 in turn completes a circuit for the escape magnet 56, which in attracting its armature moves the connector side swltch to position 2.

The calling subscriber now operates the .dial to send the tens series of impulses. With each denergization of relay 24 a circuit is completed from battery through the rotary magnet 57 and from battery through the escape relay 54 and side switch wiper 55 in parallel therewith and thence through wiper 58, back contact and left armature of test relay 59, brush 33, wiper 31, armature and back contact of relay 24 and front contact and left armature of relay 27 to ground. The brushes 60 and 61 are thus stopped from group to group of the lines terminating at the connector switch. Upon the termination of the series of impulses the relay 24 remains enerwiper 41 and the relay re- 46, wiper 45, brushline, back over the gized thus holding open the circuit for the escape relay 54, which in falling off opens the previously closed circuit for the escape magnet .56, thus moving the sideswitch to position 3.

The calling subscriber now sends the units series of impulses and with each interruption of the line a circuit is completed from battery through the vertical magnet 62 in parallel with the escape relay 54 and thus to ground over the previously traced circuit at the front contact and left armature of relay 27.

Upon the termination of the units series of impulses the circuit for relay 54 is held open and in retracting its armature completes a circuit from battery through test relay 59, the right normal contact of said relay, armature and contact of escape magnet 56, right armature and back contact of relay 54, wiper 63, brush 61 to the test contact of the called line. If the line is idle the test contact will be supplied with battery potential through the cut-off relay 2 of said line and the test relay will not be energized. As the circuit for the slow release escape magnet is now open, it retracts its armature and moves the side switch to position 4.

In position 4 a circuit is completed from battery through the cut-ofi' relay of the called line, brush 61, wiper 63 and relay 64 to ground. Relay 64 attracts its armature and completes a circuit from source of ringing current 65 through ringing trip relay 66, armature and contact of relay 64, side switch wiper 66, brush 60 over the left side of the subscribers line through the bell at the sub-station thereof back over the right side of the subscribers line to ground through relay 64. lVhen the side switch moved to position 4 a circuit was completed from battery through relay 54, wiper 55 and contact and armature of relay 66 to ground. This energized relay 54 which in turn completed a circuit for the escape magnet 56. \Vheu the called subscriber removes his receiver from the hook the increased flow of current through-relay 66 causes it to attract its armature thus interrupting the circuit for relay 54, which falls ofl and breaks the circuit for escape magnet 56, which in retracting its armature removes the side switch to position 5.

When the called subscriber removed the receiver from the hook and the connector side switch went to position 5, a circuit was completed from battery through relay 68, front contact and armature of relay 24 which is now energizedwiper 31, brush 33, wiper 45, brush 46, armature and back c0ntact of test relay 59, wiper 58, wiper 66, brush 60 over the left side of the subscribers right side of line, brush 61, and wiper 63 to ground through relay 64.

The energization of relay 68 completes Y a circuit through side switch wiper 30 in Q 5 side switch to position 4.

I It-will be noted that the battery connected to the fourth contact of wiper 23 is of opposite polarity to that connected to the first three contacts of this wiper. In position 4, a circuit extends .from battery through wiper 23,relay 24, wiper 26, brush 11, lower winding of register magnet 3, 'front contact and left armature of relay 2, over the left side of the subscribers line, back over the right side of the line, right armature and front contact of relay 2, brush 10, and wiper 21 to ground through winding20 of the repeating coil. The current which now flows through the upper winding of magnet 3 is of a polarity to assist the current through the upper winding and the magnet operates to register the call.

It will be remembered that-on the selec tion of a trunk terminating in the second selector the relay 40 was energized in series with the escape magnet 29. At this time the first selector side switch moved to position 3 and the second selector side switch to position 2. In position 3 of the first selector side switch, battery is supplied to the lower trunk conductor through resistance 70 and the front contact and right armature of relay 27, but wiper 41 now includes the resistance 81 in the circuit extending through relay 40, and this relay is deenergized and remains deenergized until the calling subscribers receiver is replaced upon its hook.

Likewise, upon the selection of the trunk terminating in the connector switch, the relay 52 was energized in series with the escape magnet 42, but as the connector side switch moves to position 2, as a result of the energization of relay 52, direct ground is removed from the circuit for said relay, and the second selector side switch moves to position 4, thus removing battery from the lower trunk conductor at this switch. Battery is still supplied to the lower trunk conductor through resistance 70 at the first selector, but relays 40 and 52 will not pull up through resistance 70 in series with the resistance of relay 64.

a When, however, the calling subscriber replaces his receiver on its hook, relay 24 will become denergized, thus opening the circuit for relay 27 which in retracting its left armature, completes a circuit from battery through release magnet 71, contact and right armature of relay 6 and from battery through release magnet 72 of the first selector, rotary oil-normal contact 73 in parallel therewith and thence to ground through the back contact and left armature of relay 27. This causes the release of the line finder as and of the first selector switch. Upon the retraction of the right armature of relay 27, battery is supplied to the lower trunk conductor, through low resistance 80. Sulficient current will now flow through the relays 40 and 52 to cause them to attract their armatures. Relay 40 closes a circuit from battery, through second selector release magnet 74 and rotary off-normal contact 75. Relay 52 closes a circuit from battery, through connector release magnet 76 and rotary off-normal contact 77. This causes the release of the second selector and the connector.

Should the calling subscriber replace his receiver on the hook during the operation of the line finding switch, relay 1 would fall off, thus opening the circuit for relay 5, which in turn would open the circuit of relay 6. Upon the deenergization of relay 6 a circuit would be completed from battery, through release magnet 71, right armature of relay 6 and the left armature of relay 27, thus releasing the line finder.

We will now assume that the wanted line is busy. It will be remembered that the units series of impulses is sent when the connector side switch is in position 3, and that at the termination of this series, the circuit of slow release relay 54 is held open causing its armatures to be retracted. Upon the retraction of the armature and while the side switch is still in position 3, a circuit is completed from battery through test relay 59, its right normal contact, armature and contact of escape magnet 56 (which being slow had not yet retracted its armature), right armature and contact of relay 54, wiper 63 and brush 61 to the test contact. If the called line is busy as a calling subscribers line, its test contact will be connected to ground through the resistance 20 of the repeating coil associated therewith; and if busy as a called subscribers line, it will be connected to ground through the relay 64 at the connector switch associated therewith. Thus relay 59 will receive current and in attracting its armature, will complete a holding circuit for itself through the front contact and inner right armature and side switch wiper 78. At its outer right armatureand front contact it completes a holding circuit for the escape magnet 56 which is thus retained energized and holds the side switch in position 3. The attraction of the left armature of relay 59 connects the busy tone apparatus 79 to the upper strand of the trunk, thus notifying the calling subscriber that the wanted line is busy. The calling subscriber will then replace his receiver upon the hook when the release of the switches used in establishing the connection will be effected in exactly the same manner as after a successful call.

What is claimed is:

1. In a telephone system, a talking connauaaeo ductor, a magnet, contacts controlled by said magnet, a relay, a circuit for said magnet extending through contacts of said relay, a test relay, and a circuit for said test relay extending through front contacts of said magnet, back contacts of said relay, and said talking conductor.

2. In a telephone exchange system, a talking conductor, a magnet, contacts controlled thereby, a relay, a circuit for said magnet extending through front contacts of said relay, a test relay, and a circuit for said test relay extending through front contacts of said magnet, back contacts of said relay, and said talking conductor.

3. In a telephone exchange system, a talking conductor, an escape magnet, a relay, means for energizing said relay, a circuit for said magnet extending through front contacts of said relay, means for deenergizing said relay upon connection being made to a wanted line, a test relay, and a circuit for said test relay extending through front contacts of said magnet, back contacts of said relay, and talking conductor.

4. In a telephone system, a conductor, a relay in parallel with a portion of said conductor, a switch for selecting said conductor to form part of a talking circuit, an energizing circuit for said relay completed upon such selection, and means controlled by said relay upon its energization for including a resistance in its circuit to cause its deenergization.

5. In a telephone system, a conductor, a relay joined to said conductor, a switch for selecting said conductor to form part of a talking circuit, an energizing circuit for said relay completed upon such selection, a circuit changing device, an operating magnet for said device, and a circuit for said magnet closed by said relay upon its energization, whereby said device is operated to include a resistance in the circuit of said relay to cause its denergization.

6. In a telephone system, a conductor, a relay in parallel with a portion of said conductor, a switch for selecting said conductor to form part of a talkin circuit, an energizing circuit for said re ay completed upon such selection, means controlled by said relay upon its energization for including a resistance in its circuit to cause its deenergization, a release magnet,

means controlled by the calling subscriber to decrease the resistance in said relay circuit to cause the subsequent energization of said relay, and a circuit for said release magnet closed upon such subse uent energization of said relay. y

7. Iii a tele one system, a conductor, a relay in para el with a portion of said conductor, a switch for selecting said conductor to form part of a talking circuit, an energizing circuit for said relay completed upon such selection, a side-switch, an escapement magnet for said side-switch, a circuit for said magnet closed by said relay upon its energization whereby said side-switch is operated to include a resistance in the circuit of said relay to cause its deenergization, a release magnet, means controlled by the calling subscriber to decrease the resistance in said relay circuit to cause the subsequent energization of said relay, and a circuit for said release magnet closed upon such subsequent energization of said relay.

8. In a telephone system, a switch, conductors extending to said switch, a second switch, a pair of talking conductors extending from said first switch to said second switch, means for transmitting impulses to said first switch, means at said switch for repeating said impulses over one of said talking conductors to said second switch to cause the operation of said second switch, and means at said first switch for transmitting an impulse over the other of said talking conductors to efiect the release of said second switch.

9. In a telephone exchange system, a switch, conductors extending to said switch, a second switch, a pair of talking conductors extending from said first switch to said second switch, operating magnets at said second switch, means for connecting said magnets to one of said talking conductors, means for transmitting impulses to the switch first mentioned, means at said first mentioned switch for repeating said impulses over one of said talking conductors to the operating magnets of said second mentioned switch, and means at said first switch for transmitting an impulse over the other of said talking conductors to efi'ect release of said second switch.

10. In a telephone exchange system, a

the

switch, conductors extendinlgxto said switch,

a second switch, a pair of ta ing conductors extending from said first switch to said second switch, operating magnets at said second switch, means for connecting said magnets to one of said talking conductors, means for transmitting impulses to the switch first mentioned, means at said first switch for repeating impulses to the mafnets of said second switch over one of sai talking conductors and testing means arranged to be associated with the other of said conductors.

In witness whereof, I hereunto subscribe my name this 31st day of December, A. 1D. 

